Dyche had an increasingly tense and difficult relationship with the previous owner Mike Garlick. He was especially furious at the end of the 2019/2020 season when the contracts of several first team players were left to run down and expire after a failure to agree extensions, publicly criticising the club's hierarchy at the time. Then to compound matters he was barely given any money during the following summer transfer window - their most expensive signing during it was Dale Stephens for less than £1 million from Brighton. All in all, Dyche leading Burnley to a 10th place finish that season, with a higher points total than what Leicester and Brighton finished with this season, was some achievement. There were strong rumours that he would leave the club at the end of that season.
Previously Dyche had been far more patient than the vast majority of other managers would have been, about the fairly limited resources available to him (certainly for modern day Premier League standards). In fact following the 2014 promotion (achieved after the club only paid a transfer fee for one player Ashley Barnes during the 3 previous transfer windows), he fully supported money being diverted away from his transfer budget on to improving their training facilities. Most other managers wouldn't have been so understanding.
Garlick is getting quite a bit of flack now from Burnley fans for not supporting Dyche more, selling to ALK capital knowing full well how dangerous it could be for the club etc.