Hi,
Thanks for the details. I must note that officially only WPML and Polylang are supported, but in this case I believe Weglot could work, as the issue is probably not related to it.
There seems to be a server side mod_rewrite redirection which removes the translate tag from the URL completely, whenever the plugin makes a request. The request is automatically redirected to the wrong URL.
For example, if you try this URL:
https://americanos.ca/pt/?asp_ls=&asp_active=1&asp_force_reset_pagination=1&p_asid=3&p_asp_data=1&termset[product_cat][]=26&aspf[region-cat__2]=Alberta&filters_initial=0&filters_changed=0&qtranslate_lang=0&woo_currency=CAD¤t_page_id=8
..it is redirected to this:
https://americanos.ca/?asp_ls&asp_active=1&asp_force_reset_pagination=1&p_asid=3&p_asp_data=1&termset%5Bproduct_cat%5D%5B0%5D=26&aspf%5Bregion-cat__2%5D=Alberta&filters_initial=0&filters_changed=0&qtranslate_lang=0&woo_currency=CAD¤t_page_id=8
And this is sort of an encoded version, but it has the /pt/ language tag removed as well.
The issue is caused by this 301 redirect rule with URL encoding. I suggest checking your .htaccess file to see if there is a redirect rule in relation with these types of URLs.