I have various sitecollections and they are behaving different. One of them, when I navigate to one of its subsites, it shows the Welcome.aspx but the URL remains unchanged, only with https://mytenant.sharepoint.com/sites/sitecol1/subsite.
The other ones, even if I type the same, it automatically changes to the following: https://mytenant.sharepoint.com/sites/sitecol2/subsite/Pages/MyWelcome.aspx.
At site settings, both have as welcome page the entire Url (with the aspx) and I tried changing the default welcome page and setting back again and did not work.
I am wondering what is causing this and if there is any setting to modify it.