First one has a light leak (possibly when you’ve removed/replaced the dark slide).
The others have mottling; possibly from too little developer, too slow in the application of the developer (pour quicker!), over agitation, under agitation, stale fixer and/or developer being too strong.
If you’re happy with all of the above not being the case, try pre-soaking. This will “spread” the initial developer contact (i.e. the most “potent” part of the development cycle) more evenly across the emulsion.
Some people don’t subscribe to ore-soaking; however, I find it necessary as I shoot very long pieces of film, and end up with uneven development if I don’t do it.