In short: probably Matlab and Python achieve similar speeds in loops.
The sources that you found are likely comparing old versions of Matlab, as @Eitan mentioned the new versions have proper Just In Time mechanisms which speed simple loops up a lot.
There will be loops that python does faster, and those that Matlab does faster, but loop speed is probably not a relevant consideration when deciding between these two languages.
solved Why are loops in matlab slower than in Python? [closed]