Parse error when i activate the Mailjet plugin

Hi,

When I activate the “Mailjet for WordPress” extension from the backoffice of a developed site, I have an error for several weeks.

The extension could not be activated because it triggered a fatal error.

Parse error: syntax error, unexpected ‘[‘, expecting ‘)’ in /data/webs/web-4027/lib/mailjet-for-wordpress/vendor/guzzlehttp/promises/src/functions.php on line 45

I do not have this concern on other websites but only on 1 in particular: https://budgetparticipatif.merignac.com/

I deleted the extension, reinstalled it with an updated version that came out in the meantime but that does not change anything.

thank you so much