Reminder that the Source engine of old Valve games still uses code from fucking Quake. Game engines using other game engine to make ultra spaghetti is not new, but it should fucking stop though.
This needs to be brought up every single time someone complains about Creation Engine being shit because it's "spaghetti code".
Source 2, the engine Valve uses for Counter Strike 2 and Half-Life; Alyx, is one of the
many offsprings of the original Quake engine.

Chances are you're using Windows right now. Be it Windows 10, 11, or 7 if you're a stubborn fuck. You're using an operating system that's a result of over three decades of constant iterations. The first version of Windows NT, Windows NT 3.1, came out in 1993, and it itself was a fork of IBM's OS/2 that first released in 1987, so technically Windows' codebase is 36 years old.
Is Source 2 an unoptimized mess that has countless of glitches, outdated graphics and is being held together by hopes and dreams? No, it's a very sophisticated engine that uses a lot of classic optimization tricks while still looking incredibly well without the need for ray tracing.
Is Windows 10/11 a barely functioning mess that keeps blue screening and crumbling at random? No, Windows at it's core is in it's best place in it's history despite it still being a 1990's OS at heart. Every feature update is a full OS update that rarely causes major issues, the system no longer shits itself at random where you have constant BSOD's and you have to reformat it, and you don't have to worry about it shitting itself when you change the motherboard.
Creation Engine being shit is all on Bethesda. It has nothing to do with it's legacy codebases. You're using technology on a daily basis that has a decades old codebase and it doesn't fail, because it was properly maintained and expanded. Bethesda's codebase is shit because Bethesda is shit.