Older versions of mafft and tools depending on it are not installable if conda-forge is higher than bioconda

[warownia1]

Following the setup instruction on the bioconda website I configured the channels as following:

conda config --add channels bioconda
conda config --add channels conda-forge
conda config --set channel_priority strict

which puts the channels in the following order

channels:
  - conda-forge
  - bioconda
  - defaults

Trying to install t-coffee I noticed that it cannot be installed due to the conflict with mafft library. It requires mafft=7.310 which is not installable.
After some investigation I found that having conda-forge channel on top makes it impossible to install versions of mafft from bioconda either explicitly or implicitly.
The command mamba install --dry-run mafft=7.310 fails with

Could not solve for environment specs
The following package could not be installed
└─ mafft 7.310** is not installable because it conflicts with any installable versions previously reported.

This error is not specific to version 7.310. All versions except for conda-forge::mafft cannot be installed.

Why has mafft been moved to conda-forge and is no longer present in the bioconda-recipes repository? It causes environment resolving issues now.

[aliciaaevans]

Can you try mamba install -c bioconda mafft=7.310 in a fresh environment? If that doesn't work, what OS and arch are you using? I am able to install that version and also t-coffee on Linux x86_64.

For the reason someone decided to add it to conda-forge, here's the original PR which has some discussion: conda-forge/staged-recipes#25606

[warownia1]

It does work when I put bioconda on top of the channels list either with conda config or -c bioconda but that means I have to change channels order for installing different packages and their dependencies. It is not possible when creating envs from the exported environemnt.yaml files.