@alexink You could just consider it $20 per year towards the expenses of running the mastodon instance. As someone who runs a mastodon instance, they may be free to join but they're not free to run and it is encouraged, regardless of what instance you are on, to seek out the donation link of your instance admin to help offset their expenses for providing the service. If you find value in the instance and the community there, then that's less than $2/mo towards the cost of that provision.