Flickr
Free accounts are limited to 1000 photos, straightforward share links (bbcode for this forum) and multiple size options

Imgur
Best used from a desktop in my experience, they removed logging in from browsers on tablets Because it was “too hard” for them to maintain lol, haven’t tried the app in over a year so might be worth looking into. Check your privacy settings before uploading - don’t “publish to imgur” and you won’t get randoms commenting on your posts

Add these letters before .jpg to resize
l = large size
m = medium size
t = thumbnail size
s = small square size

Discord
Create your own server and upload the pics there, have to be resized first if needed.

Tumblr
I’m assuming you can still hotlink from your own tumblr account, the image addresses get refreshed periodically (yearly I think) so really only for temporary hotlinking

Instagram
You can embed instagram posts (single images, not gallery/story/video posts) in this forum with a work around, try this:
https://newscrewdriver.com/2018/07/1...ithout-plugin/