Liquid Warning: Liquid syntax error (line 10): Unexpected character

1

I’ve updated from jekyll 3.3.1 to 3.5.2. I guess liquid version is upgraded to 4.0.

Here is the full warning/error:
Liquid Warning: Liquid syntax error (line 10): Unexpected character { in “{{{{category|first}} }}” in /_layouts/home.html

The following snippet was working fine for 3.3.1.:

{% for category in site.categories %}
{% assign catg = {{category|first}} %}
{% if catg == "me" %}
    {% continue %}
{% endif %}
<a href="/category/{{ category | first }}.html" >{{ category | first }}</a>
{% endfor %}

Though it seems working fine, how to resolve the warning/error?