Okay... Unity has really screwed the pooch. It's open rebellion across the internet and many have already begun retooling their workflows towards other engines, and even Unity's own employees are leaving in droves.
Long story short, Unity is WAY too greedy right now, risking serious financial harm to indies and AAA alike who use the engine. The long version is as follows. Unity has changed its terms of service and payment setup, nickel and diming you when you reach a certain amount of profit in the past 12 months and number of total installs, increasing in value the more your game takes off. This is called a "runtime fee".
"Runtime fee" starts at:
$200,000 profit in the last 12 months
200,000 detected game installs in lifetime
"Runtime fee" starts at:
$1,000,000 profit in the last 12 months
1,000,000 detected game installs in lifetime
Of course, Unity tried to walk this back and attack the flank after the rebellion started, but the floodgates are open and letting out all the river water it was supposed to hold back. They first claimed that reinstalls wouldn't trigger the fee, and then they removed their TOS from Github to hide their next move. Right now, their site says that all older versions of Unity (likely including the venerable Unity Web Player) are subject to the new terms, and thus the new "runtime fee", presumably, effective immediately.
Strictly speaking, it doesn't, because I use Godot instead of Unity. However, I too am an indie dev hopeful and it's painful seeing people like me get downright punished for their success. It's the same financial crisis that you find yourself in when you accept Epic's exclusivity deal, but instead of losing money due to cheap deals or your game suddenly becoming free and getting a sudden burst of popularity, you're actively being taxed for being too good.
These smaller game studios and solo devs often don't expect big results because of their limited capabilities, but if an indie game was to skyrocket like Cult of the Lamb or Pseudoregalia, the studio or solo in question can (and will) quickly lose ALL chances of making their investment back, much less gain a profit. This is why so many indies are in open rebellion now.
Furthermore, AAA games that use Unity, including the top mobile gacha games, some of Nintendo's games, Capcom with the now-shutting-down Mega Man X DiVE, and so on are also at risk of major financial losses because of the TOS's retroactive nature. With this, you know what's coming. The unfiltered wrath of the AAA pantheon.
If you are a budding game developer, AAA or Indie, there are options aplenty, especially for a Unity-like experience. Watch this video here to get started.