OP don't panic at the rush to hoik the bosom from some pp. Screen time is a red flag to a bull and lots of people have somewhat... erm single minded reaction because they don't entirely understand the studies with them. Same type of people who in the early 19th century would have panicked about novels ((look it up for the variety of those who don't believe me).
There's a somewhat unintelligent assertion that you couldn't possibly be doing all the wholesome things with dc at other times because usually people are just a bit sad and insecure and trying to find something that makes them feel superior for a moment because deep down they know they aren't.
So for us we did notice a relationship to tablet blue light (specifically as a small tv hasnt had the same reaction
..granted it is as old as the hills ) and we also noticed an issue with any Internet connection. Could just be my eldest dc which is where we saw it. Within 2 days he was arguing for more time.
This argument is unheard of in my house. We actually don't restrict screen time by minutes (on the grounds that it doesn't allow them to develop any actual understanding of why) they can have as long as they like as long as we are not doing something else or there isn't a task to do (dinner , activity, we are going out, teeth etc). This has resulted in them being relatively uninterested beyond about half an hour. It's not a battle so to be honest, they use screens for half an hour in the day and then get bored and wander off to do something else. (Tonight I got roped into making a cardboard Venus fly trap 
).
It has oddly meant they spend far less time on electronics than their friends if what the other parents say is true. (Don't actually care not my children not my problem)
Except with the tablet ...in bed. First and last time it caused an issue. So it was banned as the only rule is that when you are told to come off...it goes off immediately without argument. Only time that rule was ever broken was with the tablet in bed for those two nights.
However what works well for us is somewhat old fashioned (for a tech savvy ish house) the dc have an old dvd player . Yep it started when ds2 as a toddler and baby was still needing a lot of time at bed time so we tried it with ds1 (after the tablet caused an issue) . They have a few dvds and one gets put on when they first go to bed. After story (x2 but that's because currently there is a debate between whether Superheros or dinosaurs are better !) And after song ( and in our case a specific poem that keeps monsters away...but thats probably very specific to us after train line behind our old house caused havoc with two ds with very strong imaginations ). I go in to switch off half an hour later and all done. They are fast asleep a few moments later (depending on the amount of hug tax demanded by them).
Look. Find something that works for you. Ignore those who chose to put the boot in. Think about exactly what kind of human you have to be to kick someone over this. It's kind of sad ultimately. The parents I know whose dc have a healthy minimal relationship with electronics are the ones who don't have a connniption fit in an attempt to feel relevant.
Maybe try a dvd , etc where there is aspecific end point and there isnt an automatic next video suggestion.
What we found works (which I'm sure will cause a pearly clutch for someone) is I don't actually ever discuss if I take something off dc after setting a boundary. We don't get it over electronics but we do over other things. They won't be traumatised I promise. Ds2 is a talented actor. If you saw him sometimes when I say no to something you'd think the world was ending. However the drama ends because once I've explained why, it's not a discussion . There is wailing and gnashing of teeth and 5 minutes later he is off planning his next world domination.
If you get a reaction just power through. Calm , kind , steady "Nope kiddo that's the rule and you know why so that's the rule, Na night now" , a bit of wailing and done. They figure it out fast and I promise they aren't traumatised.
Mine are 9 and 6 for. reference .
Don't panic you are not a bad parent
...ignore the pp who imply you are.