Moving to Gitlab is ok, deleting 492 issues on Github us clearly not, especially when some of us proposed to help to sort them and most of them weren't resolved at all.
Members dedicated their time to document them and you just erased it, giving them the middlefinger.
This is open source, the community should own the project as much as you
This kind of f**k up after all the previous ones is close to be the last straw that broke the camel's back.
If you want to keep a community of engaged people, please learn to communicate (bis, ter, repetitae...) and avoid that kind of awfull dictator management.