Yes effecting all providers, a myth going around that a vpn will solve it but that's garbage. Somedays my 3BB is slower, other days DTAC, now AIS is faster than normal
Temperature varies with the shop and server, for independent shops i tell them and they correct for next time, some don't drink coffee so they don't know, plus no thermometer used unless Starbucks
If you look on Lazada and Shopee you'll see the year sim deals are no way near as good as they were last year with limited data, for that reason I've had 3BB fibre installed. If you are ok with 100gb of data or less then buy online