dnf5 output:
(...)
[5/5] Total                                                                                                                                                                                          100% |   0.0   B/s |   0.0   B |  00m00s
Running transaction                                                                                                                                                                                                                          
                                                                                                                                                                                                                                             
Transaction failed: Rpm transaction failed.                                                                                                                                                                                                  
  - file /usr/share/doc/sundials-doc/guide/source/figs from install of sundials-doc-6.6.2-3.fc40.noarch conflicts with file from package sundials-doc-6.5.1-5.fc40.noarch                                                                    
  - file /usr/share/doc/sundials-doc/guide/source/sunmatrix/figs from install of sundials-doc-6.6.2-3.fc40.noarch conflicts with file from package sundials-doc-6.5.1-5.fc40.noarch  

Reproducible: Always

Steps to Reproduce:
1. dnf install sundials-doc-6.5.1-5.fc40.noarch
2. dnf5 update
or 
2. dnf update
Actual Results:  
transaction check fails

Expected Results:  
no error

removing the old version and installing the new version works without issues