"[...] we can conclude that learning words from a new language does come at the cost of at least retrieval ease for words in previously learnt foreign languages.’ In one of the experiments, learning the Spanish versions of words also seemed to make participants slightly less accurate when recalling those words in English. [...]"
Although I can confirm the small effect from my own experience, it doesn't faze me. For me, the upsides far outweigh a slight delay in retrieval ease.
[1] https://psyche.co/ideas/will-studying-a-new-language-interfe...