The "complaint" is not that I don't understand _why_ this is happening, or even so much that it _is_ happening, but in my experience, this "commercialisation" of F/L/OSS is inevitably (I'd argue) net negative for the community built around it.
Even if the core product doesn't become "paid" and we don't have this issue of whether or not people _should_ have to pay to use it, the quality of the "core" or "community" product will fall, anything new or interesting will get pay-walled and updates/features will be few and far between.
I'd call this more lamentation of a loss than anything, Gitea isn't dead (yet) because of this, but I move forward cautiously to see what comes of it.
What would be really interesting, would be to revisit this discussion in a year, two, maybe more and see what became of it.
I certainly understand why those who are using software for free see this as the thin-edge-of-the-wedge, the start of the product morphing to something that is less free.
On the other hand, despite the health risks, eating is still enormously popular. Developers want to get paid, and so they tend to gravitate towards models that, well, earn money. OSS is great (I'm a fan) but it doesn't pay the bills. OSS should be what you do in your spare time, not your day job. If OSS is your day job then either you're lucky, and someone is funding it, or it's only a matter of time before you need to switch to a different day job.
Bottom line - if OSS doesn't sort out an actual funding model that works - if users (of the Libre version) aren't willing to pay real money, on a regular basis, en masse - then don't be surprised if the developers need to switch it up to earn a living.
There's this perception that "big companies" should just fund all OSS for everyone, but I'm saying that this can never work - that's pretty much exactly what "big companies" are set up not to do.