Yes. If you change 100% of your content on a certain page, it will likely affect your SEO. The reason for this is that Google and other search engines might view your page as having duplicate content. This can have a negative impact on your SEO rankings.
The level of SEO affect depends upon various factors [domain authority, topical relevance, backlinks and other page ranking signals]
If you do need to make changes to a page, it is best to only make minor edits, such as formatting or spelling corrections.
If you need to make major changes to a page, it is better to create a new page and redirect the old page to the new one. This will help avoid creating duplicate content on your site.
If you change the content of your page, it is important to ensure that the new content is high-quality and relevant to your readers.
However, if your old content was highly-optimized and well-placed in the search engines, it may take some time for the new, or fresh content to catch up.
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