max_parallel_downloads: This parameter specifies the maximum number of packages that DNF can load in parallel. The default value is usually 3 or 5, depending on your system. Decreasing the value: By decreasing the value of max_parallel_downloads, you will force DNF to load packages sequentially or in smaller groups. For example, by setting max_parallel_downloads=1, you will effectively disable parallel downloading and DNF will only download one package at a time. Speed Impact: Reducing max_parallel_downloads will cause the update process to slow down. In conclusion, reducing max_parallel_downloads is a perfectly logical way to reduce the number of DNF packages being loaded in parallel. Just be aware of the impact on speed and test different values to find the best one for your conditions.
Why? I gave the guy an answer in the comments…