I too have been a vocal advocate of GitLab for many years since first using it about six years ago. I started using it for my own projects two or three years ago and opted for the Bronze plan primarily to support GitLab as I appreciated what they provided in the free tier and liked the issue tracking features. From reading the email it sounds my money is not wanted and I’m actually costing GitLab money! Yet I could switch to free 
I use very few of the features in GitLab and I suspect I am a very light user but unfortunately one of the ones I do use - issue tracking weights and the burn down/up charts are now part of premium at $19 rather than $4. Which is far too much for a single feature. Yes I could continue for 1 or 2 more years at $4 a month but if I’m soon going to get priced out of it then I’m not sure it’s worth it. I was already half considering GitHub simply because it’s better known and it feels like GitLab is the one showing me the door. Dissapointing 