So for a non-developer that wishes to collaborate, they now need a GitHub license? That's a deal-breaker right there for any org that is composed of more than developers.
At my org we just have one user with reporter permissions on gitlab which is shared by a bunch of people who just write their name at the end of tickets or comments. For more involved people who need to be assigned to things or pinged, they pay the full license.
Something is seriously hosed with your configuration if it takes up to 30 seconds to load an issue, especially on your specs which can probably support 5000+ users. Multiple servers won't fix your problem...probably should have support eyeball your configuration.
I feel this is how Jira took off initially in orgs when they had a really affordable unlimited user tier. When hooked into LDAP/AD, suddenly every employee in the company was a user.
SaaS is a disaster without controls. They make it damn hard to automatically disable users who are no longer active. Then you have users picking competing duplicative tools, and now users can't work together without having duplicate accounts in each tool. Once they get you in, you've got no leverage--they'll just keep increasing prices because you're locked in. Companies are pushing you from perpetual license to cloud not for your benefit.
At the startup I used to work at the MD spent quite a bit of time dodging calls from Cloudinary. Every few months we needed to be on a higher tier package. We'd generally be tasked with optimising whichever metric was causing the problem a coupe of times a year (deleting / consolidating versions of various images etc).
It felt pretty shady (both his behaviour and their pricing structures).
Some of us put accounts on pause if they've been inactive for 30 days. It's not the norm (yet), but the good PR and happy customers were well worth the extra business logic.