In early June 2021, few SEOs noticed that webmaster start noticing a hike soft 404 error on Google Search Console.
John Mueller explained it in a video that Google has changed it the way how it handles soft 404 detection. It views mobile and desktop errors in a different way, but on search console, the report is available only of mobile not of desktop. So if you find any report of soft 404 of mobile in Search console then it will have an issue with mobile site, but might be possible that this issue is not with your desktop site.
John explained that this is new & surprise for him when he listen it. John explained this in the video at 21:26 time and also elaborated that this started about a month ago & they uses examples to improve the soft 404.
Check the full video for more: