In email settings (gearcog right hand top) the options for spam settings can be set to flag as spam but deliver to inbox, which what I do to avoid emails going to spam.
Only emails tagged as spam should normally go to the spam folder.
I do place emails in spam myself which gives protection by lining out links in the email so they can be viewed safely. Usually they are deleted in approx 30 days.
However recently I have noticed my spam folder is empty which means spam is deleted sooner than 30 days so can be lost.
It is common for emails to go to spam even though they are not spam, often happens to me and also happens with other email providers, and will be deleted after a number of days so wise to regular check spam folders.
Some emails can be spoofed to look as if they are from a real company but may be phishing.
I use email filters and they have not been working properly the last few days so had to check my filters and squencing of filters which can often trip up.
There is one solutuion, to use filters to identify an email from say Tesco and move it to a folder called Tesco, I have many folders set up to receive genuine emails so they do not go to the inbox or spam folder but to a named folder I have created in my folders or sub folders of archive.