Here anybody can present some open problems where
likely with limited mathematical machinary something can
be achieved (so that really junior mathematicians have a
chance to resolve this).
Likewise, also junior mathematicians can present problems.
Links:
[1] https://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] https://www.mpim-bonn.mpg.de/node/3444
[3] https://www.mpim-bonn.mpg.de/node/6098