Why did a migrated BLOB gain bytes after a text round trip?

import {DatabaseSync} from 'node:sqlite';
import {TextDecoder} from 'node:util';
import {inflateSync} from 'node:zlib';
import {posix} from 'node:path';
import {createHash} from 'node:crypto';
const rows=(db,sql)=>db.prepare(sql).all().map(r=>({...r}));
const failed=(action)=>{try{action();return null;}catch(e){return {code:e.errcode??e.code??e.name};}};

import assert from 'node:assert/strict';
const run=function run(i,corrected=true){
    const db=new DatabaseSync(':memory:');try{db.exec('CREATE TABLE target(content BLOB);');let content=i.bytes===null?null:Buffer.from(i.bytes);
      if(!corrected&&content!==null)content=Buffer.from(content.toString('utf8'),'utf8');db.prepare('INSERT INTO target VALUES(?)').run(content);
      const r=db.prepare('SELECT typeof(content) AS storage,length(content) AS length,content FROM target').get();
      return {storage:r.storage,length:r.length,bytes:r.content===null?null:[...r.content]};
    }finally{db.close();}
  };
const cases=[{"label":"misleading base","input":{"bytes":[0,255,65]},"expected":{"storage":"blob","length":5,"bytes":[0,239,191,189,65]},"corrected":false},{"label":"corrected base","input":{"bytes":[0,255,65]},"expected":{"storage":"blob","length":3,"bytes":[0,255,65]},"corrected":true},{"label":"empty BLOB retains storage kind","input":{"bytes":[]},"expected":{"storage":"blob","length":0,"bytes":[]},"corrected":true},{"label":"explicit SQL NULL is separate","input":{"bytes":null},"expected":{"storage":"null","length":null,"bytes":null},"corrected":true}];
for(const test of cases){
  const actual=run(test.input,test.corrected);
  assert.deepEqual(actual,test.expected,test.label);
  console.log(test.label,actual);
}