Illegal string offset 'altText' and PHP Notice: Only variables should be assigned by reference in IndexHandler.inc.php on line 68

Hi i got warning below when i published the ojs 3.2xx to IIS with php 7.4.11

PHP Notice: Only variables should be assigned by reference in
\pages\index\IndexHandler.inc.php on line 68
PHP Warning: Illegal string offset ‘altText’ in \cache\t_compile\54224b6b3cb68bca36d272cc8637bbdff512cab7^%%B9^B93^B932F2BF%%header.tpl.php on line 256
PHP Warning: Illegal string offset ‘altText’ in
\cache\t_compile\54224b6b3cb68bca36d272cc8637bbdff512cab7^%%40^408^4081C66E%%footer.tpl.php on line 107
PHP Warning: Illegal string offset ‘altText’ in
cache\t_compile\54224b6b3cb68bca36d272cc8637bbdff512cab7^%%40^408^4081C66E%%footer.tpl.php on line 110