My spouse and I have played NMS since release. After switching to the Steam version a number of years ago, we were lucky enough to start our current save in a system that had a paradise planet. While we weren't the first to discover the system, we were the first for the planets, flora, fauna and minerals.
Anyway, we both started bases on the paradise planet and have had those bases ever since. This planet was one of my favourites with gorgeous fields of glowing flowers (at night), purple grass, no storms, pretty water.... you get the picture.
When settlements came along, we moved our main bases to settlements, one of us on the paradise and the other on a toxic planet in the same system.
I spent many, many, many hours adding to my settlement, doing clever things to make it look nice and RPing the hell out of everything.
On the paradise planet I also turned my first base into a 'tourist attraction'. Then discovered this absolutely gorgeous flat field surrounded by hills. Inside one of the hills was a natural cave entrance. Low and behold the cave also looked spectacular with glowing fungi. So I also RP'd this as a tourist attraction - land in the field at night for a rolling field light show, enter the cave and go spelunking lit by cave roof covered in glowing fungi.....
Then the first planetary generation update came. All seemed well until I reached my 'Cave of Wonders'. The glowing fungi was gone. It was just a barren boring cave now. That hurt, but fine. It wasn't as bad as some people got as we still had a beautiful purple glowing paradise.
Then an update to settlements wrecked all my decoration. So I meticulously fixed it all and made it even better. I have cared for my settlement, made good choices for the inhabitants....
So, I was super looking forward to how beautiful our slice of paradise was going to look after the 5.0 update. I could only imagine how much more gorgeous the water and sky would look.
Imagine my horror when my spouse said that our main planet was showing as "Worm infested" when scanning. My anxiety rising I head to our paradise and my heart sinks as my ship clears the clouds. It is indeed now infested.
Worse is that my settlement is completely gone. The pin for it is still there but the settlement interface is non-existent. All that remains is all the base parts I added - now either floating in the air or completely buried as the landscape has radically changed.
I then visited every single one of my other bases. Some are still functional as the landscape hasn't changed but the planetary type has in about 90% of them (weirdly some planets are still completely the same but most are different). My runaway mould farm has been replaced by metal fingers.
Worst off is our paradise planet where both the type and landscape are different.
There's other weirdness like the Discoveries being simultaneously reset but not - it will say a planet is undiscovered but when I land, it's suddenly gets the proper info back for it. But on other systems, the discoveries are completely reset - in my AI Valve farm system, the system comes up as discovered by me but none of the planets were until I landed on them. The one that I have a base on has the name I gave it but all the other planets in the system are completely reset to their original names (and this system had some sentimental names as it was my final Atlas story system).
I'm going away for a week soon and was looking forward to playing some NMS beforehand. Now just have a sour taste in my mouth. So many hours lost and funnily enough I've lost any motivation to play at the moment. :(
My condolences. I genuinely empathize with that feeling of having lost a lot of work on something. I just wanted to add two things to the other replies:
While your awesome base may have been lost, the experience that you gained from making it is not. You're a better base builder now than you were then, and you have a seasoned eye for the kind of setting that will make for an amazing new project.
I think NMS tries very hard to (and is very successful at) teaching us to embrace ephermerality, to let go and be comfortable with the process of continually moving forward. Our character is merely one of an infinite number of instances of some entity that experiences time and space in an infinite way... All of the amazing things we have ever discovered are collectively less important than the act of discovery itself...
Even now, there is a virtually endless universe out there, with millions of sights that no one has ever seen, including -- especially -- those that you have yet to create yourself.