Action Blocks are failed like attempts. If a session (account / device / IP combination) is blocked, liking a post from the browser does not register the like on the Instagram server. Refreshing a post page after it was liked returns a non liked post.
Everliker detects such failed attempts and shows the "Failed to Like" message, stopping all tasks automatically. The action blocks are not (as far as we can see) caused by Everliker but by breaching the trust score limit.
Trust Score is a system used by Instagram to prevent like and follow functions abuse. Each action taken on a session causes that session trust score to change. Liking and following depletes the trust, while posting improves it. Trust score is only known to Instagram server and not client.
Fresh accounts and Devices have low trust scores. As the score reaches 0, certain actions are blocked automatically for that session. Trust score is restored over time. If a session was action blocked before, the overall account trust score decreases.
That depends on your account trust score which is only known on the server side.
Nowadays the safe speeds are around 300 likes / day with 500 being aggressive. But if you account was action blocked multiple times before the speed is overall lower could be lower.
You can relogin to Instagram and use a WARM UP feature to gradually build up a liking speed and figure out the limit for your account.