Delete Files in Hybrid Plans I normally would not suggest deleting versions older than 1 day. That does not provide much versioning for restore points. I guess it all depends on your negotiated RPOs with your customers. But if your customer changes a file and realizes they made a mistake and need to restore an old version, they may not be able to with those settings. In addition, if your customer is hit by some ransomware that encrypts the files in place, rather than renaming, encrypting, and deleting the originals, they may not be able to restore. I realize you have a 90 day delay on the purge, but I would rather see you use a 90 Day Retention, a specified number of versions to keep for each file, a shorter purge delay, and possibly a longer retention for locally stored files (you can have different retention settings for local and cloud).
Always Keep the Last Version will always keep the last version of every file. This is important in case a file has not been edited in 90 days, you do not want it removed from backup storage (usually).
If you are backing up volatile folders like browser cache folders and the like because they happen to be sub-folders, then my recommendation is to simply remove them from backup if not needed. Most customers do not run into issues where files deleted as a normal part of business results in noticeable changes to storage.