This is going to be vague for obvious reasons.
I worked on an EDA product for a short time. Its code base had a few components, some of which were written by the product team, and some of which were copied (without source history) from other teams. The team decided to make a cloud version of the product too, and to do that, the team split in half and each new team had their own copy of the code base.
No sharing code, because those other teams were our competition. There were teams working on components for our product, and another team working on a copy of our product, but nobody shared code. So bugfixes from one of the components would never make it into our code base. (The components were products in their own right.)
The code base was ~30 years old, and it had "survived" a port from Unix to Windows. The build system was a hellish nightmare of Cygwin, makefiles, Perl scripts, hard-coded paths, and unsupported internal tools, and after ~2 hours of manual fiddling it spat out a build. A few million lines of code, which according to my tests, would take ~10 minutes to build with a proper build system. I have a proper rant about the horrors I saw in the build system, I had never imagined that a build system could be so bad, and whenever I mentioned the name of the internal tool it was built on, company veterans on other teams would recoil.
Meanwhile, I witnessed how much damage the other developers were doing to the product. Some were trying to catch up with feature requests, some were adding hacks to the core algorithm to try and improve numerical stability, and some were doing real damage to the code base by adding buggy and poorly designed features--think major performance regressions, memory errors, and deadlocks fixed by adding calls to Sleep().
I tried to improve things as much as I could there. The company culture had some upsides (good work/life balance) but the internal competition strangled innovation, the wrong people made technical decisions, and the team didn't have a balanced set of skills.
The product hasn't been "killed" per se. It's still for sale. But it's the walking dead. Being EDA, licenses can run into five figures per seat, but the product's revenue was on a downward trend last time I checked. I have a couple friends that still work on the team but I'm encouraging them to apply for new jobs. I left when I got an offer from a major (big five) tech company.