Default [Q] [Help] Downloads from email apps delete themselves after 2 days

I download my schedule from my email every week. Thing is, the pdf disappears from my phone after two days, without fail. I thought maybe it was all downloads, but I've got a pdf of a remote manual I downloaded in Chrome from a few weeks ago as well as pictures from a reddit app that didn't disappear.

I thought maybe it was my file browser (ES) so I uninstalled it and tried Solid Explorer. Same issue. Interestingly, this issue occurs in both the stock email app as well as the gmail app. I have different accounts (both gmail) associated with both.

I've restarted my phone, but that does not help. I think it might have something to do with Download Manager or the Downloads app, but I have no idea how to test this or to change settings. Can they be disabled safely? Does anyone have any idea what could be going on? I don't have any space saving/clearing apps, nor have I ever installed any.

EDIT: NM, there doesn't seem to be any rhyme or reason to what is saved and what isn't. Everything I downloaded last night has been cleared from my downloads folder. Not even 24 full hours. Perhaps the reboot clears it? This will require further testing.