To decide myself how much tip to give rather than have 12.5% or 15% already added on to the bill, in England

[Jossse]

I enjoy going out for food and drinks with friends and family. I have over the past 6 months or so, noticed that some establishments have started to add on 12.5% and 15% to the bill total. This is happening even when buying at the bar or and or ordering on an app.
I’ve always added on 10% for good service and more if exceptional, and rounded up most of the time.
We are all aware that food and drink prices are now much higher and also there is a national minimum wage.
I want to choose how much tip I leave for my server/waiting staff rather than have 12.5% and 15% added on to my bill. When I have questioned this, the manager has needed to come along and speak and authorise this, making the whole experience awkward.
Back in the day (pre Covid/2000) before this was happening, I was a waitress and earned good tips. I put in effort to ensure my customers enjoyed their experience. Sadly a lot of waiting staff today do not seem to understand about customer service, I’m guessing because they already are earning the tip from the bill.
One company said the extra 2.5% was so that the waiting staff didn’t have to pay the card payment charge!
So, AIBU to want to add my own service tip or should the establishment add it in for me when presenting the bill.

I just do it instead of service charge. Unlike some people I'm not made of money

And it's nothing to do with handing a plate empty or not. That's just basics and hardly tip worthy. It's the attitude and friendliness of the wait staff

I agree about the team, without the pot wash keeping me supplied with clean cutlery, the bar staff delivering the right drinks in good time and the chefs making good food in a good time, I wouldn't be able to give good service, it's all part of it, most people consider it poor service to wait for the wrong drinks, or cold food, or cutlery because there's none clean.
Even in places that haven't stipulated sharing tips, I always have, because I'm not a one man band, I can't cook and I couldn't do pot wash for hours on end either (it's a gruelling, dirty job but essential) and if that means forgoing a tip then so be it, being friendly and amenable is in the job description, but I wouldn't be able to switch up items (or completely rewrite the menu!) or even make adjustments if it weren't for the cooperation of the kitchen team or bar team, chefs, pot wash and bar staff have all ran food or dirty pots when I'm busy to free me up to be there for the guests - it adds to the overall service provided.