No its normal contingency planning in case of emergency. People are getting wound up about this because there has been more publicity than normal.
It is true the UK has been close to capacity in previous years and thats caused concern. And the situation is more likely in parts of the EU which were more heavily reliant on Russian Gas.
HOWEVER variation measures have been put into place to try and improve our energy security this winter (of course this doesn't get well publicised like these timetables because its not clickbaity). Also some power companies are doing dynamic pricing to help customers save money and to spread the demand on the grid during the day to avoid peak time useage being higher than the network can deal with (it something people may want to look into if they are struggling with bills).
If you look on your bills there should be a small letter on it above your name. Thats your area code. If there are brownouts they will either be at the start of the week or the end of the week depending on your code. Not all week. Its usually a max of 3 blocks and they are at various times of the day. And each block will be a small area or estate, with the next one over unaffected.
Not everywhere will be affected across the country - there are certain areas of the country where the grid has more capacity than others. I think the SW, South of Wales and the SE are much more vulnerable to problems than the North generally speaking.
I stress that I personally think its still extremely unlikely we will see issues. Demand is definitely down on previous years and people are being a lot more conscious about using energy more efficiently. I think this effect will cover much of the concern / gap in energy supply this year. We only imported a small amount of Russian gas, and we can cover this by sensible usage (without going crazy either) this winter if every does things like switch off lights when you leave a room or more people run energy intensive things off peak where possible.
This one is largely a case of a media frenzy feeding on people's anxieties and extra interest in energy prices and availability.
It is possible we may have problems, but if have a worse case scenario, I really don't think it will be longer than a week in duration. Which means you'd get 2 maybe 3 cuts and thats it. Which is both managable and people should be able to cope with this as a matter of course by default because there is always the risk of power cuts. 3 hours is a pain in the bum, but its also not long and if its very localised.
In short: Don't panic